C1. Congenital conditions (Anterior)

Question 1

what is coloboma? 7 structures affected?

Answer 1

Incomplete closure of the embryonic orbital fissure (during embryological development)

Can affect several structures:
lids, iris, ciliary body, lens, retina, choroid or optic disc
May co-exist

Question 2

what is iris coloboma?

Answer 2

“Typical” iris colobomas are located in the inferonasal quadrant. They are caused by failure of the embryonic fissure to close in the 5th week of gestation, resulting in a “keyhole-shaped” pupil.

Question 3

2 consequences of iris coloboma?

Answer 3

photophobia in bright conditions
glare

Question 4

Mx for iris coloboma?

Answer 4

special contact lens fitted that covers the keyhole-shaped pupil and makes it look round

improves the cosmetic appearance of the eye as well as reducing light sensitivity

For some people, surgery is an option, where the gap in the iris is sewn together to correct the pupil shape and reduce light sensitivity.

Question 5

what is lens coloboma?

Answer 5

flattening of the equator of the lens in an area of absence of zonular fibers.

best visualized in a dilated eye and may be incidentally diagnosed as they are almost always asymptomatic

Question 6

consequences of lens coloboma?

Answer 6

Vision may be affected because of the change in lens shape caused by a notch or dent.

There may also be some degree of cataract in the affected eye
can cause symptoms such as blurred or misty vision, colours appearing dull and glare

Question 7

Mx for lens coloboma?

Answer 7

Refractive error should be treated with corrective lenses.

If severe and unable to correct with manifest refraction, consider lens extraction with IOL placement to prevent amblyopia from developing.

Care should be taken, however, as zonular abnormalities exist and may complicate surgery.

Question 8

Mx for colobomas in general?

Answer 8

No medication or surgery that can cure or reverse coloboma and make the eye whole again

Correcting any refractive error with glasses or contact lenses.

Maximizing the vision of the most affected eye in asymmetric cases

Ensuring that amblyopia (lazy eye) does not develop in childhood in case of asymmetry.

Sometimes amblyopia treatment (patching, glasses and/or drops) can improve vision in eyes even with severe colobomas.

Treating any other eye condition that may be present with coloboma, such as cataracts.

Treating any complications that might arise from a retinal coloboma later in life, such as the growth of new blood vessels at the back of the eye (neovascularization) and/or retinal detachment.

Using low vision devices

Genetic counselling

Question 9

what is megalocornea? what gene type? systemic association?

Answer 9

HVID of 13mm or larger

X-linked recessive, 90% affected are males

Systemic associations: Marfan syndrome, Ehlers-Danlos syndrome, Down syndrome

Question 10

Ocular associations with megalocornea?

Answer 10

Associated with high myopia and astigmatism
Deep anterior chamber
Normal vision and IOP

Question 11

assessments and mx for megalocornea?

Answer 11

Assessment::
Rule out congenital glaucoma

Mx:
Px reassurance and education

Question 12

what is microcornea? AD or AR?

Answer 12

HVID of 10mm or less
Autosomal dominant

Question 13

associations with microcornea?

Answer 13

Associated with hyperopia and shallow anterior chamber
Normal vision

Question 14

assessments and mx for microcornea?

Answer 14

Assessment
Risk of high IOPs

Plan
Routine glaucoma screening

Question 15

what is aniridia?

Answer 15

Bilateral absence of the iris, can be total or small stump of the iris base (iris hypoplasia)

Question 16

associations with aniridia?

Answer 16

Ectopia lentis

Cataract

Foveal & optic nerve hypoplasia

Nystagmus

Conjunctivalization of the peripheral cornea

Question 17

SSx of aniridia?

Answer 17

Glare

Poor vision, 6/60 or worse

Dry eyes

Question 18

assessment and mx for aniridia?

Answer 18

Assessment:

Check for glaucoma

Mx:
Cosmetic CL
Low vision aids
Sunglasses
Artificial implantable iris
Refer for genetic counselling

Question 19

what is albinism?

Answer 19

Melanocytes are present but do not produce melanin

White hair, pale skin, pink eyes

Question 20

subjective and objective for albinism?

Answer 20

Subjective:
-Poor vision
-Photophobia

Objective:
-VA to worse than 6/120
-High myopia and astigmatism
-Nystagmus
-Macular hypoplasia
-Poor RPE function

Question 21

assessment and mx for albinism?

Answer 21

Assessment:
Handle px with meticulous care

mx
Low vision aids
Refer for genetic counselling
Dark sunglasses
Good protection against UV (they are easily sunburnt)

Question 22

what is heterochromia irides?

Answer 22

Asymmetric colour of the two irides
Can be congenital or secondary to disease process

Question 23

assessment and Mx for heterochromia?

Answer 23

Assessment
DDx: Fuchs heterochromia cyclitis, siderosis, iris melanosis, iris melanoma

Mx:
Px reassurance and education
Photodocument

Question 24

what is persistent pupillary membrane?

Answer 24

Strand of iris linking to iris
Can be broken due to pupil dilatation
Sticks on anterior lens capsule or
Floats in anterior chamber

Question 25

Mx for persistent pupillary membrane?

Answer 25

Management

During the first year of life, most PPMs undergo atrophy and require no treatment.

Membranes persisting after one year are less likely to regress spontaneously, increasing the risk of deprivational amblyopia.

Small PPMs can be managed conservatively. Mydriatics, refractive correction, and patching for amblyopia have been used successfully in such cases.

Thick, fibrotic membranes may require surgical excision. Surgery is generally performed in the first weeks or months of life, with good visual prognosis

Question 26

what is ectopia lentis? cause?

Answer 26

Ectopia lentis is the dislocation or displacement of the natural crystalline lens.

Caused by weakened or deformed zonules

Question 27

define a luxated lens and a subluxated lens

Answer 27

The lens is defined as luxated (dislocated) when it lies completely outside of the hyaloid fossa, is free-floating in the vitreous, is in the anterior chamber, or lies directly on the retina.

The lens is considered subluxed when it is partially displaced but remains within the lens space.

Question 28

subjective and objective for ectopia lentis?

Answer 28

Subjective:
monocular diplopia

Objective:
Onset in teenagers
Myopia and astigmatism

Question 29

Mx for ectopia lentis?

Answer 29

Annual monitoring of VA and Rx to prevent refractive amblyopia

Advised against contact sports

­As many predisposing diseases are hereditary, genetic counselling may be indicated